Seismic risk

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Seismic risk takes the results of seismic hazard analysis, and calculates the 'follies of man'. Your safety depends on what you build. You can locate in a region of high seismic hazard, but still sleep fairly soundly at night if you have built to sound engineering principles. On the other hand, you can be located in a region such as New York City, in an ancient, poorly maintained brick building, suffering settlement problems on a filled swamp. While New York has a history of only minor seismicity, the risk in this case might be as high or higher than in a well-built building in a high seismicity zone.

A special subset is urban seismic risk which looks at the specific issues of cities. As well, risk calculations and emergency response can be improved through the use of an Earthquake scenario.

[edit] Calculations of seismic risk

Seismic risk calculations are the foundation for risk mitigation decision-making, a key step in risk management. Large corporations analyze their 'portfolio' of properties, to determine how to best allocate limited funds for structural strengthening of buildings, or other risk reduction measures such as emergency planning. In calculating the risk of each facility in the 'portfolio', potential life safety and economic losses due not only to structural damage, but also to equipment, contents and business interruption are considered. Public agencies (local, state governments and federal agencies) similarly analyze their portfolios. For 'lifelines' such as water, road and highway, electric power etc systems, the interconnectedness of the network is considered. Lastly, insurance companies routinely employ estimates of seismic risk in their operations, to determine appropriate insurance rates, to monitor over-accumulation of policies in a small area, and to purchase reinsurance.

To estimate seismic risk, computer programs take all the seismic hazard inputs, and combine them with the known susceptibilities of structures and facilities, such as buildings, bridges, electrical power switching stations etc. The result gives probabilities for economic damage or casualties. While the results can be used as a general measure of seismic risk for types of buildings, the actual seismic risk for any individual building may vary considerably and will depend upon its exact configuration and condition. Acquiring and analyzing the specific data for an individual building or facility is one of the most expensive and daunting aspects of seismic risk estimation

[edit] Reduction of seismic risk

Seismic risk can be reduced by active programs that improve emergency response, and improve basic infrastructure. You can improve your own situation through earthquake preparedness. Building codes are intended to help to manage seismic risk and are constantly being updated as more is learned about the effects of seismic ground motion on buildings. However, the changes generally do not immediately improve seismic risk in a community since existing buildings are rarely required to be upgraded to meet the revisions.